Communication system



H. J. NICHOLS ET AL COMMUNICATION SYSTEM Filed March 26, 1935 Sept. 13,1938.

2 Sheets-Sheet 1 [a Xa zz 3 K6 IX;

R Urvf ATTORNEYS Sept. 13, 1938. c o s ET AL 2,129,779

COMMUNICATION SYSTEM Filed March 26, 1936 2 Sheets-Sheet 2 Fnq: 5

ATTORNEYS Patented Sept. 13, 1938 UNITED STATES PATENT OFFICECOMMUNICATION SYSTEM Application March 26,

16 Claims.

This invention relates to communication systems and more particularly tothe control of the sending operation of the transmitter in a printingtelegraph system or the like.

More particularly the invention relates to a printing telegraph systemof the synchronous, single impulse type. In a typical system of thischaracter a keyboard is provided at the transmitter, the individual keysof which are associated with segments of a rotary distributor andarranged to control the signal transmission when the distributor makescontact with a segment associated with an operated key. A second rotarydistributor is provided at the receiving station which is caused tooperate synchronously with that at the sending station, and which isutilized to selectively operate suitable printing apparatus inaccordance with the signals sent by the transmitter. It is important ina system of this character that signals be sent to the line in the orderin which the keys are depressed and also that all signals sent to theline are of equal length regardless of the length of time a key is helddepressed by the operator. that, should the operator hold the keydepressed an unnecessary length of time, only one signal be sent foreach key operation, and that no repeat signals be sent.

It will also be apparent that in a certain minor average number of casesa-key will be depressed when the rotary distributor is in contact withits associated segment. Under these circumstances, particularly when thekey is depressed just as a distributor is about to leave the segment, acasual partial or "clipped signal will occur. Such clipped signals are aprobable source of error. They may fail to actuate line relays, or othersignal controlling devices causing a failure or omission of the printingoperation; or may 40 delay operation until the receiving distributor hascontacted the following segment causing the wrong character to beprinted, or causing the printing of two adjacent characters by reason ofthe operating impulse carrying over from one segment to the next. Whilethe production of clipped signals (where no preventive measure is taken)occurs as a. matter of chance, such signals will on the average cause acertain proportion of errors depending upon various characteristics ofthe telegraph system.

It is accordingly the principal object of the invention therefore toprovide a communication system which will assure the sending of properand uniform signals to the line under all condi tions of use.

It is also important 1936, Serial No. 70,924

It is a further object to provide a transmitting apparatus whichprovides for the sending under all conditions of a single uniform signalto the line regardless oi the time when, or the length of time, a key atthe transmitter is operated.

It is a further object to provide a transmitting apparatus which with aminimum delay in the transmission will eflectively avoid thetransmission of clipped signals.

It is a still further object to provide a simple and effectivesignalling method of sending single uniform signals to the line inresponse to the operation of the transmitter.

Other objects and advantages will be apparent from the followingdescription, the accompanying drawings, and the appended claims.

In the drawings:

Fig. 1 shows in diagrammatic form the elements of one embodiment of theinvention as applied to a typical single impulse system, all partsexcept those relating to the signal sending function being omitted tofacilitate the showing and description of the essential features of theinven tion.

Fig. 2 shows in similar form another embodiment of the invention wherebyclipped signals and unintentional repeat signals are suppressed.

Fi 3 shows in similar form a variation in the arrangement shown in Fig.2, in which the auxiliary relay is energized by the charge stored in acapacitor.

Fig. 4 shows in similar manner another embodiment of the invention asapplied to a single impulse system in which the signals aredifi'erentiated as to polarity as well as in respect to time,illustrating the method by which clipped signals and repeat signals areprevented.

Fig. 5 is a diagram in similar form showing arrangement of Fig. 4combined with other control features to provide a complete singleimpulse transmission system as applied to a typical modern printingtelegraph.

Fig. 6 is a diagram showing a modified arrangement for assuring thetransmission of proper signals particularly adapted to a systemutilizi-ng capacitor or like means in the signal transmission circuit.

Referring to Fig. 1. which illustrates particularly the aspect of theinvention relating to suppression of partial or clipped signals whichmight occur by chance when a key is depressed at the instant when therotary contactor has partly traversed the segment operatively associatedwith that particular key. The elements of the transmitter material tothe present description comprise a rotary distributor 2B, which consistsof a series of insulated stationary contact members or segmentsdesignated a, b, etc., two only being shown, these two representing aseries corresponding to the keys, Ka, Kb, etc., of the key board. Thedistributor also includes a stationary ring 2|, and a rotary contactor22 which connects the segments in proper sequence to the ring. Thesegments and ring are in practice preferably arranged in concentriccircles and are swept over at uniform speed by rotary contactor 22. Thedistributor elements are shown in linear development in order tosimplify the diagram.

The series of sending keys Kc, Kb, etc., actuated by the operator, areadapted to operate individual key switches Xa, Xb, etc., by suitablemechanical means, as for example by push rods, but for simplicity thekeys and key switches are shown combined. The key switches arepreferably of break-make type, the effect of depressing a key being toopen the break contacts (top and middle springs) and to close the makecontacts (middle and bottom springs). The middle or tongue spring ofeach key switch is connected directly to its associated segment; the topspring is connected to a common circuit called receive bus 23, and thebottom spring to a common circuit called send bus 26. A pivoted memberl5, called the universal bail (shown in cross-section), is mountedtransversely underneath all keys in such manner that when any key isdepressed, the bail I5 operates auxiliary switch X which may be providedwith any desired contact combination, in this case a simple makecombination being shown. Auxiliary switch X cooperates with the keyswitches and the r'otary distributor in controlling an auxiliary relayKR, which in turn controls the sending circuits to assure accuracy intransmission of the signals to the line. The source of direct current,which may be a battery, but in accordance with modern practice ispreferably a rectifier unit, is indicated at B, the negative side beinggrounded. Resistance R represents any type of line coupling device. Theconnections and circuits will be more fully described in connection withthe description of the operations of the arrangement.

The operation of the arrangement shown in Fig. 1 is as follows: Let itbe assumed that rotary contactor 22 is sweeping over the distributor inthe direction indicated and that key Kb has been depressed by theoperator Just before contactor 22 has reached segment a, next insequence before segment b. Simultaneously with the closing of the lowercontacts of key switch Xb, the contacts 24 of auxiliary switch X areclosed by universal bail l5, likewise actuated by key Kb. When contactor22 reaches segment a, an auxiliary control circuit is completed frompositive battery via conductor Ill called the positive bus, ring 2|,contactor 22, segment a, tongue and upper contacts of key switch Xa,receive bus 23, conductor 24, through the winding of KR, conductor 25,via contacts 2--3 of switch X to ground, thence returning to negativebattery. A current pulse through the circuit just traced, termed theauxiliary circuit, energizes relay XR, closing contacts 4-5. Thecharacteristics of relay XR are such that in the brief intervals whencontactor 22 is passing between adjacent segments associated withnon-operated keys it will not open its contacts 4-5., Thus whencontactor 22 reaches segment 2:, a circuit is established from ring 2|,via contactor 22, segment b, middle to lower contacts of key switch Xb,thence to send bus 28,

conductor 28, through resistor R to ground. A current pulse through thecircuit just traced, termed the sending circuit, continuing so long ascrush 22 contacts segment b, produces a voltage across R, and hencetransmits a corresponding signal impulse to the line. This signalconstitutes a full printing signal. When key Kb is released, thepressure on universal bail I5 is released, the spring tongue of switch Xopens its contacts and relay XR is deenergized, opening contacts 45,thus restoring the circuits to normal condition.

Next let it be assumed that key Ka is depressed by the operator at aninstant when rotary contactor 22 is in contact with segment a. In suchevent, the tongue and upper contacts of key switch Xa are opened and thetongue and lower contacts are closed, connecting the segment to send bus26. Simultaneously, bail I5 closes contacts 2-3 of auxiliary switch X.Thus the auxiliary circuit is incomplete at key switch Xa, and thesending circuit being open at contacts --5, the transmission of thesignal is prevented. However, when rotary contactor 22 reaches asucceeding segment associated with a non-operated key, as for examplesegment b, the auxiliary circuit is closed from ring 2| via contactor 22to segment b via upper contacts of key switch Xb to receive bus 23, byconductor 24, winding of relay XR and contacts 2-3 of auxiliary switch Xto ground. Relay XR is energized by thecurrent pulse through theauxiliary circuit, closing contacts l5, thus completing the sendingcircuit. Near the end of the revolution, assuming that key Ka remainsdepressed, when contactor 22 again reaches segment a, a full signal issent to the line. Upon the release oi key Ka, the circuits are restoredto normal condition as previously described.

It will be observed that the circuit associated with an operated key isenergized upon operation thereof. The corresponding contact segmenthowever is not immediately energized, but becomes energized only afterthe cooperation of the rotary contactor with a segment corresponding toa. non-operated key. In the event a key is depressed at the instant therotary contactor is in contact with the segment associated with anoperated key, the sending of the signal is delayed until the followingrevolution. Thus partial or clipped signals, which would otherwise occurwhen a key is depressed too late, i. e., when the contactor has alreadytraversed part of the connected segment, are suppressed, and all signalssent to the line are of full length and are properly timed.

Referring now to Fig. 2, the arrangement there shown combines theclipped signal suppressor function of Fig. 1 with a non-repeat function.In Fig. l, in case the depressed key were held down for more than onerevolution of the rotary contactor, a second signal could betransmitted. Such unintentional repeat signals are prevented by thearrangement to be described. The elements of the arrangement aregenerally similar to those described in connection with Fig. 1. In thisarrangement, however, auxiliary switch X is provided with three springsforming a break-make combination designated by I, 2, 3; a capacitor C isconnected in series with the tongue 2 of switch X, and a resistor R2 inseries with the upper spring I; auxiliary relay XR is provided with anadditional pair of make springs designated by 8, I, and with threewindings designated by wl, w2, w3. The circuit connections will be madeclear in describing the operation.

The operation 01' the arrangement shown in Fig. 2 in sending is asfollows: Assume that key Kb has been depressed, breaking the upper andmiddle contacts, and closing the middle and lower contacts 02 key switchXb, and by means of bail l5, breaking contacts I-2 and making contacts2-3 01' auxiliary switch X. When contactor 22 reaches segment a (or anysegment associated with a non-actuated key), an auxiliary circuit isestablished Irom positive battery, conductor i9, ring 2| via contactor22 to segment a, tongue and upper contacts of switch Xa to receive bus22, via conductor 24, contacts 3-2 of K, through capacitor 0. conductor24', through winding 10! of relay XR and conductor 25 to negativebattery. A current pulse flows through this circuit, charging capacitorC and energizing relay KR. which operates, closing contacts 4-5 and 8-1.These latter contacts apply holding current to relay KR from positivebus l9, contacts 8-1, through windings 102 and wl, via conductor 25 tonegative battery. When contactor 22 reaches segment b, the sendingsegment, an impulse is transmitted through the circuit from positivebattery, conductor i9, ring 2| via contactor 22, segment b, tongue andlower contact of key switch Xb, to send bus 26, through conductor 21 andwinding w3, via contacts 4-5 and resistor R to ground. The voltage dropcaused by this impulse flowing through resistor R causes thetransmission of a signal to the line for the duration of. the traverseof contactor 22 across segment b. The current impulse through winding:03, which is connected in opposing relation to the other windings, isarranged to neutralize the effect 01' the holding current in windings wland w2; hence relay KR is de-energized and drops out, opening itsholding circuit and contacts 4-5 and 6-1.

This arrangement thus provides positive assurance that no more than onesignal will be transmitted for any one operation oi a key regardless ofthe length of time the key is depressed. Thus if key Kc remainsdepressed over a number of revolutions of contactor 22, the contactorcloses the circuit above described each time it contacts a segmentassociated with a non-actuated key. Condenser C remains charged howeverand hence no substantial current pulse through winding wl occurssuiilcient to cause actuation of relay XR. Such current flow as mayoccur is sufficient to maintain the charge on the condenser butinsufficient to effect actuation of the relay. The sending circuittherefore remains open at contacts 4-5 and successive repeat signals arenot sent to the line in response to contactor 22 closing the sendingcircuit at the segment corresponding to the actuated key.

This condition prevails until the depressed key is released, permittingcontacts 2-2 (of switch X) to open and contacts 2| to close. The closingof the latter contacts permits capacitor C to discharge through thecircuit containing R2, the function of which is to limit the dischargecurrent of C, reducing the tendency of burning or arcing at contactsl-2. This completes the operating cycle, restoring the circuit toinitial condition.

Assuming next that key Ka has been depressed just as contactor 22reaches, or is on, segment a, then no signal can be sent from segment a,since the sending circuit is open at contacts 4-! of relay XR. When,however, contactor 22 reaches segment b, the auxiliary circuit isestablished and relay XR energized as described above, ex-

cept that the circuit is initially completed from ring 2i via contactor22 to segment b. The signal impulse is transmitted when contactor 22again reaches segment a in its next subsequent rotation, in like mannerto the transmission via segment b described above. The invention thusprovides means assuring that regardless of the time when or the lengthof time during which a key is depressed, a single proper full signal issent to the line, and the sending of clipped and non-repeat signals isefiectiveiy prevented.

Referring now to Fig. 3, the arrangement shown provides a modified meansfor securing non-repeat action. In this arrangement a condenser C isconnected in a circuit including positive battery and the middle andupper normally closed contacts 2-l of auxiliary switch X, chargingresistor R2 to ground and negative battery. Thus the condenser isnormally charged by battery B. l

The operation of this arrangement is as follows: Assume that key Kb hasbeen depressed when contactor 22 is in the position shown. Whencontactor 22 reaches segment a, or any other segment associated with anon-operated key, an auxiliary circuit is established from conductor I!connected to the positive side oi. condenser C, ring 2| via contactor 22to segment 0. via tongue and upper contact of key switch Xa, to receivebus 23, conductor 24 through winding wi, conductor 25, via contacts 3-201 auxiliary switch X to negative side of charged capacitor C. Thecharge on capacitor C is rapidly discharged through the circuit justtraced, quickly energizing relay m which operates, closing its contacts4-! and 6-1. Contacts 4-5 establish the sending circuit, while contacts6-1 apply holding current to winding 1122, holding KR in operatedcondition. The holding current is obtained from one o! the sections ofbattery B, say section B, since a reduced voltage ordinarily sufflces tosupply the required holding current.

When contactor 22 reaches sending segment b, the signal impulse istransmitted over the sending circuit, which may be traced from positivebattery, conductor [9, ring 2! via contactor 22 to segment b via tongueand lower contacts of Xb to send bus 26, thence by conductor 21 throughwinding wfl, contacts 4-5 across resistor R to negative battery. Thevoltage drop across R causes the transmission of a corresponding signalto the line. The local impulse, flowing in winding w! in opposition tothe current in winding m2, sunlcientiy neutralizes the flux in relay XRthat it releases its contact springs which open contacts 4-5 and 6-1.Opening of. contacts 4-5 prevents sending oi repeat signals to the line.Relay XR can not reoperate, pending the reverse operation of switch X,since its operating energy is derived from capacitor C which wasentirely discharged on the first operation of XR. When the depressed keyis released, contacts 2-3 of switch X open, and contacts' 2-I close,whereupon capacitor C is immediately recharged from battery 18.

Assuming next that key Kc were depressed 4 with contactor 22 in theposition shown, or in ,contact with segment a, no signal can be transanon-operated key, the auxiliary circuit is e tabllshed, capacitor Cdischarges through winding wl to energize XR as described above, and thesending circuit is established by the closing of contacts 4-5. Whencontactor 12 again reaches segment a, the local sending impulse flows inthe sending circuit, transmitting a signal to the line and de-energizingXR, preventing repeat signals, as explained above. When the depressedkey is released, capacitor C is recharged, and the circuits restored tonormal condition.

This modified arrangement thus also eflectively assures proper sendingconditions and provides against the sending of clipped or rep atsignals. This arrangement has the further advantage that the energy foroperating the auxiliary relay is obtained from the power supply inadvance or the transmitting operation and stored in condenser C, andthus does not reduce the voltage of the current source when needed forgenerating the signal impulse even though the operation of relay XRoccurs immediately prior to the sending of the signal. This promotesuniformity in the amplitude of the transmitted signals. An amplequantity of energy for operating the auxiliary relay may be stored incapacitor C, and when required may be very quickly discharged throughthe relay winding, producing very rapid action.

Referring now to Fig. 4, the arrangement there shown is an embodiment ofthe invention as applied to a single impulse system in which the signalsare differentiated as to polarity as well as in respect to time. Thedistributor 2|! is in this case provided with two series of segmentspreferably grouped in pairs, the arrangement being such that one seriesof segments transmits signals of one polarity to the line, while theother series transmits signals of opposite polarity. The sending circuitis shown as being coupedto the line by resistors R and R whose junctionis grounded, but other line coupling arrangements may be used asdesired. Two sending and two receiving busses are provided, beingnumbered 26, 2G and 23, 23' respectively. Signals sent via send bus 26may be regarded ashaving positive polarity, and those sent via send bus26 as having negative polarity. Rotary contactor 22 contacts a pair ofsegments simultaneously, but since only one key of a pair is depressedat the same time, only one signal is transmitted. Auxiliary relay XR. isprovided with contacts 4 to H, the purpose of which will be hereinafterdescribed. Auxiliary switch X is provided with bail it which is adaptedto be operated simultaneously with the operation of any of the keys.

The operation in transmission is as i'ollows:- Assume that key Kc isdepressed Just as contactor 22 reaches paired segments a, b, or anyother pair oi segments associated with non-operated keys, closing thetongue of key switch Xc to the lower contact. Bail ll simultaneouslycloses the tongue oi! auxiliary switch X to the lower contact. Anauxiliary control circuit is set up from positive battery via contacts1-8 of relay XR, conductor 23', upper contacts of key switch Xb, segmentb, via contactor 22 to seg-. ment a, via upper contacts oi key switch Xato send bus 23, conductor 24, via contacts l|ll), through winding wl,conductor 34, through capacitor C, lower contacts of switch X to ground.The current pulse through this circuit energizes relay XR. and chargescondenser C. Upon op eration, relay XR opens contacts 1-8, iD-ll and.closes contacts 45, 8-1, 9-40. Contacts 6-1 appy positive current viaconductor I! to ring 2i, contacts 9-40 apply holding current to windingwl via a circuit including conductor 34, res stor R3, lower contacts oi!switch X to ground. Q

Contacts 4- -5 establish the sending circuit. Resistor R3 is made ofrelatively high value so that it passes only sufllcient current to holdrelay XR. operated but not enough current to cause relay XR, to pull inwhen de-energized.

When contactor 22 reaches segment 0, the sending circuit is completed asfollows: From positive battery, contacts B'|, conductor 09, ring 2| viacontactor 22 to segment 0, via lower contacts of X0 to send bus 26, viaconductor 21, through winding 103 via. contacts 4-5, conductor 28,resistor R to ground. The current impulse through the circuit tracedsends a positive signal to the line, and acting through opposing winding103 neutralizes the flux in relay XR which drops out, opening thecontacts closed when it operated. Resistor B! being of high value, onlya small leakage of the charge on capacitor occurs, and this charge iscontinually replenished each time contactor 22 contacts a pair ofsegments associated with non-operated keys. The chargingcurrent flowingat any one time in the auxiliary circuit under these circumstances isvery small and insufllcient to cause relay XR to pull in.

Relay XR "thus remains unoperated until the depressed key is released,permitting capacitor C to be discharged through the upper contacts ofswitch X and discharge resistor R2, thus providing non-repeat action. Ifit is assumed that key Kd were depressed, rather than key Kc, under theconditions stated above the analysis would be the same, except that thesignal impulse is sent via segment d, key switch Xd, send bus 26',conductor 21' and resistor Rl to ground, causing a negative polaritysignal to be sent to the line.

Assuming next that key Ka is depressed when contactor 22 is traversingsegment a, .it will be evident irom the foregoing analysis that theauxiliary control circuit will be open at key switch Xa, hence relay KRwill not be operated, its contacts l5 are open, and consequently asignal cannot be transmitted until the next revolution of contactor 22.In case key Kb is depressed when contactor 22 is in contact with segmentb, and the auxiliary circuit will be open at key switch Xb, and theoperation of relay XR cannot occur until a succeeding segment associatedwith a non-operated key is contacted and the signal cannot be sent tothe line until the next revolution of contactor 22. It will therefore beevident that the transmission of proper uniform signals is assured andthe transmission of clipped signals and repeat signals is effectivelyprevented.

Referring now to Fig. 5, the arrangement there shown illustrates anembodiment of the invention as applied to a single impulse system inwhich the signals are diflerentiated with respect to polarity as well asto time, with key board control and interlock means. The distributor 20is provided with two series of segments grouped in pairs as described inconnection with Fig. 4. Four keys and associated apparatus are shown,these being representative of a complete key board for transmittingletters and signs in the well known manner of the typewriter. All keylevers are preferably at the same level, their outer ends projecting ina uniform row in such manner that all keys are capable of operatinguniversal bail l5 and can be controlled by latch means presently to bedescribed. The latch is actuated by latch magnet LM shown in operativerelation to latch bar 30 which ispivotally mounted on the frame of themachine, and is provided with 8A position of latch associated with keyKa). Aux-.

iliary relay XR is provided with three windings ml, 102, wit and withcontact 4 to l2, the purpose of which will become clear in thedescription of the operation.

The operation in transmissionis as follows: A capacitor C is arranged tobe normally maintained in charged condition by means of a circuitincluding positive battery, normally closed contacts 1-8 of relay KR,condenser C, normally closed middle and upper contacts of auxiliaryswitch X, and charging resistor R2 to ground. Assuming that key Kc hasbeen depressed as shown, when contactor 22 reaches segments a, b,(segments associated with a non-operated key) an auxiliary circuit isestablished from positive side of condenser C, via conductor 33 toreceive bus 23', tongue and upper contact of key switch X6 to segment1:, via contactor 22 to segment a, via tongue and upper contact of keyswitch Xa to receive bus 23, by conductor 24 through winding ml andconductor 34, and via lower and middle contacts of auxiliary switch X tonegative side of charged capacitor C which now discharges through thecircuit traced. A current pulse through this circuit energizes relay XRwhich operates, opening contacts 1- 8 and closing contacts 4-5, B-'|,9-40, ll|2. Contacts 4--5, ll|2 establish the sending circuits; contacts6-1 applypositive battery to ring 2| through winding 103; contacts 9-"!apply holding cur-- rent to winding 102, and operating current to latchmagnet-,LM through a circuit including battery B, conductor 35, windingw2, conductor 36, winding LM, conductor 31, contacts 9-40 to frame andthence returning to negative battery. Magnet LM is shownconnected inseries with winding wZ, but may be connected in parallel a resistor R toframe and thence returning to negative battery. The voltage dropappearing across resistor R due to the local current impulse in thecircuit just traced sends a signal of positive polarity to the line. Thecurrent impulse through winding :03 produces a flux counter to that ofwinding w2, de-energizing relay XR. and releasing the contact springswhich return to. normal position as shown. This breaks the sendingcircuit at'contacts 4-5 and Ill2, hence repeat signals cannot be sent tothe line. Re-operation of XR. is prevented by the lack of charge oncapacitor C which was discharged at the beginning of the sending cycle.Potential is removed from ring 2| when contacts 6-,-! open. Contacts9-40 open the circuit supplying current to winding m2 and to latchmagnet LM, de-energizing same and releasing latch 20, which is restoredto un-operated position by retractile spring 3| thus releasing thedepressed key. As the released key returns to normal position under theinfluence 'of a suitable spring means, the tongue'of auxiliary switch Xshifts to the upper contact, permitting battery B to charge capacitor Cthrough resistor R2, thus restoring all circuits to initial normalcondition.

Assuming next that contactor 22 is on segment 0 when key Kc isdepressed, the associated key switch Xa has its tongue depressed so thatthe auxiliary circuit upon which operating winding ml of relay XR.depends for operating current is open, and hence the sending circuit isnot established until the pair of segments next in sequence arecontacted. It will thus be apparent without further detailed analysisthat the section of the auxiliary circuit between receiving bus'ses 26and 26 will be interrupted when any key is depressed when in contactwith contactor 22; the circuit may only be closed and signalstransmitted following the actuation of a key when contactor 22 firstcontacts a pair of segments other than those associated with theoperated key. Hence provision is made for sending full length signals ofthe proper characters and clipped signals are effectively prevented.

The operation of the system is substantially the same for every otherkey. Thus for example when key Kd is operated, an auxiliary circuit isestablished when contactor reaches a pair of segments associated with anon-operated key such as segments a, 1), including positive sidecapacitor C, upper contacts of key switches Xu and Xb, and throughwinding wl oirelay XR as described above. Relay KR is energized,connects in its own holding circuit, energizes latching magnet LM andestablishes the sending circuit through its contacts 4'-5, so that whencontactor 22 reaches segment d, a sending pulse or signal is sent to theline. The circuit for this pulse is from positive battery, contacts6--7, winding w3,

ring 21, via contactor 22 to tongue and lower contact of key switch Xd,via send bus 26', conductor 21', contacts 45, conductor 28', throughresistor Rl to frame and negative. The voltage drop across resistor BIis in the opposite direction to that occurring when key Kc is depressed,and sends a signal of negative polarity to the line. The remainder ofthe operation is the same as described above for the operation of keyKc. Thus assurance is provided for the proper transmission of signals ofdesired characteristics upon the operation of any of the keys of themachine.

It should be noted that upon depressing a key, the operated key islatched down, and all unoperated keys are locked against possibledepression until after the signal is transmitted, hence the signals areperforce sent in the order in which the keys are depressed. The keylatch also holds the operated key down until the signal is sent, eventhough the operator merely strikes the key and releases it. In case thekey is held ,too long, unintentional repeat signals are not transmitted.

It thus becomes clear that the invention, in a simple and practicalmanner, assures the satisfactory transmission of proper signals withoutattention by the operator. The method and ap-- paratus disclosed permitsthe operator to transmit easily and accurately merely by observing areasonable cadence within the speed limitations of the system. are

Re! ,ri-ing now to the modification of Fig. 6.

there is shown an embodiment of the invention as applied to atransmitting arrangement in which the printing signals are initiated bythe discharge'oi' individual capacitors associated with the sendingkeys, eachkey Kc, Kb, etc., is provided with an individual capacitor Ca,Cb, etc., connected in such manner that upon depression oi a key thecapacitor is charged from the battery B, and upon the release of thekey, the capacitor is discharged to initiate the sending of a signal. Anauxiliary re'lay XR is provided to control the sending circuit as inprior embodiments. The resistor R represents any line coupling means andmay be a relay, transformer, or other suitable device. The distributoris pro.- vided with one or more pairs of special segments p, p" withwhich the rotary contactor 22 coacts to complete the auxiliarycontrol'c'ircuit, although a separate distributor or othersuitablealternative means may be employed. A universal ball If, operated incommon by the sending keys as inprior examples, actuates the auxiliaryswitch X. The-.circuit connections will be traced in describing theoperation.

The operation is as follows: Assume that key Ka is depressed, then withthe key in the depressed position, capacitor Cu is charged irom positivebus l9 via the tongue and lower contact oi. the associated key switchKa, through capacitor Ca to negative bus 29. Simultaneously, universalbail l5-is pushed down by key Ka and closes the lower contacts ofauxiliary switch x. charging capacitor C. Upon release of key Kc,retractile means (not shown) moves the key to close the upper contactsof the key switch, and at the same time the upper contacts 0! auxiliaryswitch X are permitted to close. When rotary contactor 22 reachessegment a, no signal is sent because the sending circuit is open atcontacts 4-5 of relay, KR. When rotary contactor 22 contacts the pairedsegments p, a circuit is set up from negative bus 28 via capacitor 0,via upper contacts of auxiliary switch x, conductor 24, via pairedcontacts 12', by conductor 25 through winding wi of relay KR. tonegative bus 29. Capacitor C discharges through the circuit just traced,energizing relay 12R which closes contacts 4-5, thus establishing thesending circuit. Holding current for relay XR is furnished throughresistor R2, which is made of such value that the current is sumcient tohold relay KR in operated position, but is not suihcient to operate therelay in the absence or the operating current provided by capacitor C.When contactor 22 again reaches segment a, capacitor Ca dischargesthrough the circuit including the upper contacts of key switch Km, fromsegment a via contactor 22 to ring 2i, by conductor 21, contacts 4-5 andthrough opposing winding :02 of relay KR, through resistor R, tonegative bus 29. The current pulse caused by the discharge 0! capacitorCa through this circuit produces ayoltage across resistor R sending asignal to the line. The curreni'fthrough opposing winding 102deenergizes relay XR, which releases to permit contacts 4-4 to open,thus opening the sending circuit and preventing unintentional repeatsignals.

Since the auxiliary control circuit must be completed by means 0!segments not included in the sending circuit, casual partial ormutilated signals are prevented in the event contactor 22 is in contactwith a segment associated with the sending key at the instant of releaseof the key. Assuming that key Ka is closed. at the 'forms of apparatusfor instant when the contactor 22 paired segments 1), it will be eenthat when contactor 22 makes contact/wit segment a, the sending circuitwill not ,be" closed, hence another revolution oi the rotary contactorwill be re-' quired in order to transmit the-signal. Such is just beyonddelay in transmission may be reduced by pro-,

Iii

While the methods herein described, and the carrying these methods intoeiiect, constitute preferred embodiments of the invention, it is to beunderstood that the invention is not limited to these precise methodsand forms oi apparatus, and that changes may be made in either withoutdeparting from the scope oi the invention which is defined in theappended claims.

What is claimed is:

l. A communication system of the character described comprising aplurality of operable members, means for transmitting timed impulses ofcertain time duration upon the operation of each of said members, andmeans providing for the transmission or a complete impulse for everyoperation of said members, including means controlled by said members,irrespective of the time of operation of said members, to eiiecttransmission of impulses 01' equal time duration.

2. A communication system of the character described comprising aplurality of individual circuits. periodic means sequentiallycooperating with "said circuits to condition each said circuit fortransmitting conditions, means for energizing said circuits selectivelyto cause the transmission ci a signal impulse upon cooperation oi saidperiodic means with the particular circuit energized, andmeans'controlled by the second mentioned means to delay the energizationoi certain of said circuits at certain times to prevent the transmissionof apartial sighal impulse.

3. A communication system of the character described comprising aplurality of diflerent circuits, periodic means sequentially cooperatingwith said circuits, means for cuits to cause the transmission of asignal impulse upon cooperation of said periodic means with theparticular circuit energized, and means controlled by the secondmentioned means to delay the transmission of an impulse when any of saidcircuits is energized during the time that said periodic means is incooperative relationship with that circuit.

4. A communication system of the character described comprising aplurality of diiferent circuits, periodic means sequentially cooperatingwith said circuits, means for energizing said circuits to cause thetransmission 01 a signal impulse upon cooperation ot said,pericdic meanswith the particular circuit energized, and means controlled by thesecond mentioned means to suppress the transmission of an impulse inresponse to energization of one of said circuits unless energizaticn ofsaidcircuit has been completed prior to the cooperation oi said periodicenergizing said cir- 7 tive characteristics upon the operation of eachof the several keys, and means controlled by the first mentioned meansto suppress the transmission of a signal impulse upon operation of eachof the said keys at certain times to prevent the transmission of apartial signal impulse.

6. A communication system of the character described comprising aplurality of operable keys, circuits associated respectively with saidkeys adapted to be conditioned upon operation 01' each of said keys,means cooperating with each of said circuits sequentially to transmit atimed signal upon cooperation thereof with a conditioned circuit, andmeans controlled by the said keys to delay the transmission of thesignals in the event that the particular circuits are not conditionedprior to the cooperation of the said means therewith.

7. In a communication system of the character described, a plurality ofcircuits, means to condition said circuits, a transmission circuit,periodic means cooperating with said plurality of circuits sequentiallyto energize the transmission circuit upon cooperation with theconditioned circuits, means to delay the energization of saidtransmission circuit in the event that the circuits are not conditionedprior to cooperation of the said periodic means therewith, and meanscontrolled by the said first mentioned means so as to operate upon theconditioning of any one of said first mentioned circuits to prevent theconditioning of any other of the said first mentioned circuits until theenergization of the said transmission circuit has been effected.

8. In a communication system of the character described a plurality ofoperable members, circuits associated respectively with said membersadapted to be conditioned upon operation of each of said members, atransmission circuit, periodic means cooperating with said firstmentioned circuits sequentially to energize the transmission circuitupon cooperation with the conditioned circuits. means to delay theenergization of said transmission circuit in the event that the circuitsare not conditioned prior to cooperation of the said periodic meanstherewith, and means to maintain the circuits associated with saidoperated members conditioned until the energization of the transmissioncircuit is effected.

9. In a communication system of the character described a plurality ofoperable members, circuits associated respectively with said membersadapted to be conditioned upon operation of each of said members, atransmission circuit, periodic means cooperating with said plurality ofcircuits sequentially to energize the transmission circuit uponcooperation with the conditioned circuits, means to delay theenergization of the transmission circuit in the event that the saidcircuits are not conditioned prior to cooperation of the said periodicmeans therewith, means to maintain the circuits associated with the saidoperated members conditioned until the energization of the transmissioncircuit is effected, and means operated upon the operation of saidmember to prevent operation of the others of said members until afterthe energization of the transmission circuit is effected.

10. A communication system of the character described comprising aplurality of operable members, circuits associated with the membersadapted to be energized upon the operation thereof, a plurality ofcontacts corresponding to said circuits, a movable member periodicallyengaging said contacts in sequence, means for transmitting a signal inresponse to engagement of said member with an energized contact, andmeans controlled by said operable members for energizing the contactcorresponding to an energized circuit only when said member is inengagement with a contact corresponding to a non-energized circuit.

11. A communication system of the character described which comprises aplurality of operable members, periodically moving means having acooperative sequential relation with said members, means providing forthe transmission of a signal of timed characteristics upon thecooperation of said moving means with an operated memher, and meanscontrolled by the operable members effecting a delay in the transmissionof said signal until a succeeding cooperative relation when operation ofsaid member occurs during the existence 01' a cooperative relationbetween said means and said member.

12. A communication system of the character described which comprises aplurality of operable members, periodically moving means having acooperative sequentlal relation with said members, means providing forthe transmission of a signal of timed characteristics upon thecooperation of said moving means with an operated member, and meanscontrolled by said members to delay the transmission of a signal untilthe moving means has first established cooperative relation with anon-operated member.

13. A communication system of the character described comprising, incombination, a plurality of control circuits, periodic means tocooperate with said circuits sequentially, a transmission circuit, meansto condition the control circuits to effect energization of thetransmission circuit upon cooperation of the periodic means with theconditioned circuits, and means controlled by the second mentioned meansto maintain the transmission circuit deenergized in the event that thecontrol circuits are not conditioned prior to the cooperation of theperiodic means therewith.

14. A communication system of the character described comprising, incombination, a control circuit, means to condition said circuit, atransmission circuit to transmit signal impulses, periodic meanscooperating with said circuit to energize said transmission circuit uponcooperation with the conditioned circuit, and means controlled by thefirst mentioned means controlling the transmission circuit to maintainit deenergized upon the transmission of the signal irrespective of thenumber of times said periodic means cooperates with the conditionedcircuit.

15. A communication system of the character described comprising, incombination, a plurality of operable members, circuits associated withmembers and adapted to be conditioned upon operation of thecorresponding members, a circuit for the transmission of signalimpulses, periodic means cooperating with said circuits sequentially toenergize the transmission circuit upon cooperation with a conditionedcircuit, and means controlled by said members to maintain thetransmission circuit deenergized thereafter irrespective of the lengthof time the member remains operated to condition the associated circuitthereby limiting the transmission of the signals to one for eachconditioned circuit.

16. A communication system of the character described comprising, incombination, a plurality of operable members, circuits associated withsaid members and adapted to be conditioned upon operation of thecorresponding members, a circuit for the transmission of signalimpulses, periodic means cooperating with the said circuits sequentiallyto energize the transmission circuit upon cooperation with a conditionedcircuit, means to maintain the transmission circuit deenergized aftertransmitting a signal irrespective oi the length of time the said memberis operated and the associated circuit remains conditioned and meanscontrolled by said members to prevent the operation of others of saidmembers until the transmission of the said signal.

HARRY J. NICHOLS. I-IEN'RY L. THOL-STRUP.

D l S C L A I M E R 2,129,779.-Harry J. Nichols, Binghamton, and HenryL. Tholstrup, Endwell, N. Y.

COMMUNICATION SYSTEM.

Patent dated September 13, 1938. Disclaimer filed March 15, 1941, by theassignee, International Business Machines Corporation.

Hereb flicial Gazette April 8, 1941.]

enters this disclaimer to claims 1 to 6 inclusive, and claims 8, 9, and11.

eration of the corresponding members, a circuit for the transmission ofsignal impulses, periodic means cooperating with the said circuitssequentially to energize the transmission circuit upon cooperation witha conditioned circuit, means to maintain the transmission circuitdeenergized after transmitting a signal irrespective oi the length oftime the said member is operated and the associated circuit remainsconditioned and means controlled by said members to prevent theoperation of others of said members until the transmission of the saidsignal.

HARRY J. NICHOLS. I-IEN'RY L. THOL-STRUP.

D l S C L A I M E R 2,129,779.-Harry J. Nichols, Binghamton, and HenryL. Tholstrup, Endwell, N. Y.

COMMUNICATION SYSTEM.

Patent dated September 13, 1938. Disclaimer filed March 15, 1941, by theassignee, International Business Machines Corporation.

Hereb flicial Gazette April 8, 1941.]

enters this disclaimer to claims 1 to 6 inclusive, and claims 8, 9, and11.

